Electric switching device



Jan. 23, 1962 A. LENNING 3,018,348

ELECTRIC SWITCHING DEVICE Filed June 5, 1959 INVENTOR. /4/\/c//" Len/7. 1;

BYOQQ g OQaNZJL ATTORNEYS United States Patent 3,018,348 ELECTRIC SWITCHING DEVICE Alvar Lenning, Stockholm, Sweden, assignor to AB Inreco, Stockholm, Stockholm, Sweden, a registered manufacturing corporation Filed June 5, 1959, Ser. No. 818,398

8 Claims. (Cl. Nth-164) My invention relates to an electric switching device, such as an impulse relay. Characteristic features of it are: a push rod which co-operates with two contact carrying leaf springs, said springs being set at an angle and so arranged that they exert force against each other with their inwardly projecting movable end portions; a link member hinged to, and separating, said spring end portions, said link member having a limited angular movability and formingin conjunction with the leaf springs-a mechanical system having two distinct states of stable equilibrium. Each full stroke of the push rod serves to cause a shifting performance of the system between said two states of equilibrium.

It is known to employ in a switch mechanism two cooperating leaf springs set in approximately right angles,

and where one spring at a time, by means of its free tip, keeps the second spring deflected, say into a contact producing position. One disadvantage inherent in this type of switch rests with the obvious fact that the sliding movement of one spring tip under the influence of spring force from the other gives rise to considerable friction which in turn requires an excessive operational coil wattage in case the device is being used in a relay. Other design difficulties relate to providing adequate insulation between co-operating springs. As far as is known no practical solution to these problems has been found up to this time.

In the new invention the aforementioned problems have been solved in a simple and effective way. The frictional forces have been materially reduced, and energy will in fact, during the switching action, be recuperated from the spring being released. This to a large extent reduces the operational coil wattage required.

The invention will presently be described more in detail in reference to the accompanying drawing which shows an embodiment in the form of an impulse relay (a relay in which a brief current impulse produces a lasting switch action). FIG. 1 shows such a relay-in one of its characteristic states of rest where one pair of contacts is in makeposition, and a second pair in break position. In FIG. 2 is shown, in larger scale, a knee action link joint which is incorporated as a detail in all the other figures. FIG. 3 illustrates the final phase in a switching from the FIG. 1 position. A modification of the relay in accordance with the preceding figures is illustrated in FIG. 4. All the figures have the numeral designations in common, wherever this is practical.

In FIG. 1 numeral 1 denotes a conventional magnet coil, and numeral 2 a vertically disposed armature core of soft steel which is free to move in the coil. The core is tubular and has near its bottom end an inside offset adapted to carry a conical weight 3 having a central push rod 4. Above the magnet coil are two co-operating and mutually inclining leaf springs, 5 and 6, which are at their outer ends clamped into insulating blocks, 9 and 10, respectively. Said insulating blocks are also carrying two counter springs, 5a and 6a. The spring pair 5 and 5a has mutually co-operating silver contacts (not denoted by numerals), and the spring pairs 6 and 6a likewise. At their tips the springs 5 and 6 are equipped with insulating members, 50 and 60, having lug shaped hinge means for a uniting, or rather separating, link member 7. On the bottom faces of the insulating members cavities 8a and 8b are provided, for receiving and guiding the push 3,018,348 Patented Jan. 23, 1962 rod 4. The numeral designations (8a and 8b) have been omitted in FIG. 1 but are included in FIG. 2 which shows the linkage system in larger scale. It will be seen from FIG. 2 that link member 7 is equipped with a central tongue to interact with, and form a stop 11 against, the insulating members, thus limiting the angular movability of the link. The general arrangement is such that the link 7 in conjunction with spring 6 and its insulating member 6c forms a knee action joint which in the position shown has moved to a stop slightly beyond its dead center. The spring So, as a consequence, is stably deflected towards the left by means of the link member 7 and the spring 6a. In this stable position contact between springs 5 and 5a is being established.

An opposite and equally stable position of rest is shown in FIG. 3 where the contact between springs 6 and 6a is closed whereas the former contact between 5 and 5a has been interrupted. Since the linkage system is symmetrical it follows that the mechanical system comprising members 5, 7 and 6 possesses two states of stable equilibrium. as no intermediate state of such nature (disregarding frictional forces) exists. Said two positions of stable equilibrium are represented by FIGS. 1 and 3.

That modification of design which is illustrated in FIG. 4 serves to show how the same meehancial principle will apply to an impulse relay having a polarized armature core (NS), in which case the magnet coil has to be fed with direct current only.

The device in accordance with FIGS. 1, 2, and 3 works as follows, assuming that FIG. 1 represents the starting position. As a current impulse is imparted to the magnet coil 1 the armature core 2 shoots upwardly, bringing along the weight 3 and its push rod 4. The rod hits the bottom of the cavity 8b in the insulating member 60. This causes a shift from the original state of equilibrium of members 5, 7, and 6 into that state which is shown in FIG. 3. One might observe in FIG. 3 that the push rod 4 in the course of its action tilts over a certain angle towards the right. As the magnet coil is subsequently de-energized the core 2 drops back into its original position of rest, thus permitting the push rod to resume its original vertical position. The rod will thereby be ready for its next stroke, this time against the cavity in the insulating member Sc (FIG. 3) Which will by this time be situated directly above the push rod.

In the embodiment according to FIG. 4 the armature core 2 is polarized and therefore comprises a permanent magnet as shown. Accordingly the core and its rod will in their upwardly directed motion perform a tilting action towards the right or left, depending upon the direction of the energizing current. A shift in the contacting will take place only as the direction of the energizing current is being reversed. Repeating a current impulse without current reversal will apparently not alfect the contacting mode of the relay. It will be necessary in the embodiment shown in FIG. 4 to provide means (not shown) to prevent the armature core from turning around its axis.

The invention as illustrated in FIGS. 1, 2, and 3 is equally applicable to switches for manual actuation in which case a push button or its equivalent is to be substituted for the armature core and the magnet coil.

I claim:

1. An electrical switching device comprising, in combination, a pair of stationary contacts, a pair of movable contacts one adapted to engage each of said stationary contacts, a pair of resilient blade members each carrying one of said movable contacts, said blades forming an angle with each other and the resilience of said blades biasing said blades toward each other, a link member pivotally interconnecting the free ends of said blades, said link member comprising a stop limiting the movement of said member to a predetermined angle beyond dead center position with respect to each blade, to thereby move one of said movable contacts into engagement with its associated stationary contact at each end position of said link, whereby the resilience of the blade Whose contact is in non-engaging position servesto hold the contact of the other blade in engaging position, and operating means for rocking said link member through. its dead center position.

2; A device according to claim: 1- wherein said link is.

provided with means at either end thereof to cooperate with said operating means.

3'. A device according to claim 2 in which said operating'means is actuated by an electromagnet.

4. A device according to claim 2 wherein said operating means; comprises a push rod and said cooperating means on said link ends comprises a plate-like member having a cavity therein.

5. A device according to claim 4 wherein said limiting means comprises an abutment on said link which cooperates with said plate members on said link ends.

6. A device according to claim 5 wherein said operating means comprises means for moving said push rod substantially along its axis, said means permitting said push rod to incline from its axial position after reception of its end in said cavity of one ofsaid plates.

7. A device according to claim 6 wherein said means for moving said push rod is an electromagnet, said magnet having a hollow movable core with a bottom at right angles to its Walls and wherein said push rod has a member of circular cross-section at its end remote from said plates, said member being perpendicular to the rod axis and being urged to seat on said core bottom.

8-. A device in accordance with claim 6 Whereinsaid means for moving said push rod, is an electromagnethaving a Winding and an armature fixed to said rod, said armature comprising a permanent magnet whereby the direction of current flow through said winding, determines which of the plate cavities will be engaged bysaid push rod and permits operation of said link from one end position to the other only upon reversal of current in said electromagnet winding.

References Cited in the file of this patent UNITED STATES PATENTS 2,477,166 Berry et al July 26, 1949- 2,574,399 Lamb Nov. 6,1951 2,601,545 Miller June 24, 1952 2,902,559 Morris Sept. 1,,1959 2,908,781 Brunicardi Oct 13, 1959 2,917,598 Foster Dec. 15, 1959 

